Wobbly front crank. Easy to fix?

[Bayerd]

My front crank has started to rock when pedaling. I'm asuming that it's probably fairly easy to fix by replacing. Do I need any specialist tools? and is there anything else I need to consider?

It's a Halfords BSO MTB btw.

I'd be grateful if anyone could offer advice or point me in the right direction.

 

[chillyuk]

I don't understand "front crank". You only have two on a bike, one each side between the bottom bracket and the pedals. Could you clarify the part that is loose and I am sure you will get the advice you need.

 

[ianrauk]

if it's a Halfords MTB I can imagine it's a square tapered bottom bracket and crank set. If that's the case it may just need re-tightening, however if it has been lose a long time then you may have rounded of the BB which would mean a new one of those.

 

[Theseus]

Could you clarify something ....

Are the cranks moving in relation to the bottom bracket or is the bottom bracket loose in the frame?

 

[Tollers]

undo the cover at the bottom bracket....then tighten the bold behind it!

 

[Bayerd]

I apologise for my poor terminology. From what Chilly describes it's the bottom bracket. I've only noticed it this morning so should be (hopefully) in early stages of wear. If it only needs tightening, how do I go about that?

It's the crancks in relation to the bottom bracket.

 

[Bayerd]

Could this be the answer?

http://bicycletutor.com/cartridge-bottom-bracket/

 

[gbb]

If its the standard square taper on most BSOs, you probably need a 14mm socket and ratchet.

 

[Tollers]

i doubt very much that you need to replace the BB.

I would try this first http://bicycletutor.com/replace-cotterless-cranks/

 

[Bayerd]

Will do Tollers, thanks!

 

[Bayerd]

Oh bugger, went to the LBS to get the problem sorted, he couldn't budge the BB. I've a mate who could remove the old BB, so I thought I'd get another off t'internet and the get round to his workshop and fit the new one.

How do I know which size I need? I thought they were universal.....

 

[Norm]

There are a lot of options, different lengths, different diameters, different cranks, I think there might even be a couple of different thread pitches. Take 2 seconds to look at the options on Sheldon Brown's page, to see the number of varieties.

The only way to know is to take out the old one and measure.